Törmä H, Vahlquist A
J Invest Dermatol. 1987 Apr;88(4):398-402. doi: 10.1111/1523-1747.ep12469726.
In an attempt to characterize the enzyme(s) responsible for retinol esterification in hairless mouse epidermis, various subcellular fractions were incubated with [3H]retinol and the reaction products (retinyl esters) isolated by high-performance liquid chromatography. The microsomal fraction exhibited the highest esterifying activity and was stimulated by the addition of palmitoyl-CoA and dithiothreitol, but not by palmitic acid. Saturation kinetics with an apparent Km of about 6 microM for retinol were noted. Experiments with competitive and noncompetitive inhibitors of [3H]retinol esterification established that the epidermal enzyme was an acyl-CoA:retinol acyltransferase (ARAT; EC 2.3.1.76). The specificity for retinol was not absolute; a few closely related vitamin A alcohols were equally good substrates. The ARAT activity was not significantly altered by physiologic variations in the epidermal vitamin A content. In conclusion, mouse epidermis expresses ARAT activity which may be of importance for the regulation of vitamin A metabolism at the cellular level.
为了鉴定负责无毛小鼠表皮中视黄醇酯化的酶，将各种亚细胞组分与[3H]视黄醇一起孵育，并通过高效液相色谱法分离反应产物（视黄酯）。微粒体组分表现出最高的酯化活性，并且通过添加棕榈酰辅酶A和二硫苏糖醇而受到刺激，但不受棕榈酸的刺激。观察到视黄醇的表观Km约为6 microM的饱和动力学。用[3H]视黄醇酯化的竞争性和非竞争性抑制剂进行的实验确定，表皮酶是一种酰基辅酶A：视黄醇酰基转移酶（ARAT；EC 2.3.1.76）。对视黄醇的特异性不是绝对的；一些密切相关的维生素A醇也是同样好的底物。表皮维生素A含量的生理变化不会显著改变ARAT活性。总之，小鼠表皮表达ARAT活性，这可能对细胞水平上维生素A代谢的调节很重要。
